IP Address Starvation: Why IPv4 Is Running Out

IP address starvation is the exhaustion of available IPv4 addresses, the 32-bit numeric labels that identify devices on the internet. IPv4 is scarce because its 4.3 billion possible addresses, designed in the early 1980s, cannot accommodate the billions of smartphones, computers, servers, and IoT devices connected today. This article explains the mechanics of IPv4 exhaustion, its consequences, and the transition to IPv6.

Formula

The calculator above estimates the remaining IPv4 address pool. The formula is simple:

• Total IPv4 addresses = 2^32 = 4,294,967,296
• Addresses remaining = Total − Addresses in use
• Percentage used = (Addresses in use ÷ Total) × 100

All variables are plain counts of addresses. The “in use� figure is an estimate because the exact number of allocated vs. truly active addresses is not publicly known; many allocated addresses are reserved or unused.

Worked Example

Using the default values from the calculator:

1. Total IPv4 addresses = 4,294,967,296
2. Addresses in use (estimated) = 3,700,000,000
3. Remaining = 4,294,967,296 − 3,700,000,000 = 594,967,296
4. Percentage used = (3,700,000,000 ÷ 4,294,967,296) × 100 = 86.15%

So with those estimates, about 595 million addresses remain, and 86% of the IPv4 space is already used. The exact number of “free� addresses fluctuates as regional registries allocate blocks.

Why IPv4 Was Designed the Way It Was

IPv4 (Internet Protocol version 4) was standardized in 1981 as part of the ARPANET’s evolution into the internet. The 32-bit address field allows 2^32 combinations, which seemed vast at the time. The designers did not anticipate the explosive growth of personal computing, mobile phones, cloud services, and always-on broadband. In 1981, a few hundred hosts existed; today, the number of internet-connected devices is in the tens of billions.

The address space is not distributed equally. Large chunks are reserved for special purposes: private networks (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16), loopback (127.0.0.0/8), link-local (169.254.0.0/16), multicast, and future use. These reservations reduce the number of publicly routable addresses to roughly 3.7 billion, and many of those are allocated to organizations that may not use them efficiently.

How IPv4 Exhaustion Happened

The Internet Assigned Numbers Authority (IANA) allocated the last large IPv4 blocks to the five Regional Internet Registries (RIRs) in 2011. Each RIR then began distributing its own pool. APNIC (Asia-Pacific) exhausted its pool in 2011, RIPE NCC (Europe, Middle East, Central Asia) in 2019, and ARIN (North America) in 2015. LACNIC (Latin America) and AFRINIC (Africa) still have some space but face the same eventual depletion.

Exhaustion does not mean the internet stops working. It means no new addresses are available from the free pool. Organizations must rely on secondary markets, network address translation (NAT), or IPv6.

What Happens When IPv4 Runs Out

Without new IPv4 addresses, internet service providers (ISPs) cannot assign a unique public address to every customer. Common workarounds include:

• Carrier-Grade NAT (CGNAT): ISPs share one public IPv4 address among many customers, with each household using a private address behind the ISP’s router.
• IPv6 deployment: IPv6 uses 128-bit addresses (2^128 possible), providing an astronomically larger space. However, IPv6 is not backward-compatible, so dual-stack operation (running both protocols) is common during transition.
• Secondary markets: Companies buy and sell used IPv4 blocks, often at high prices, which has created a trading ecosystem.

For end users, the most visible effect is that some devices may not have a public IPv4 address, which can complicate hosting servers, peer-to-peer connections, or accessing certain services that require direct addressing.

Common Misconceptions

One frequent misunderstanding is that “IPv4 is gone� or “the internet is full.� In reality, the free pool is depleted, but the internet continues to function through NAT and IPv6. Another misconception is that IPv6 will replace IPv4 overnight. The transition has been slow because NAT allows IPv4 to keep working, and many networks lack the incentive to migrate. Also, some people think IPv6 is more secure – it is not inherently; security depends on configuration.

How IPv6 Solves the Problem

IPv6 expands the address space to 340 undecillion addresses (2^128). It also simplifies packet headers, improves autoconfiguration, and eliminates the need for NAT in most cases. However, IPv6 adoption has been uneven. As of the mid-2020s, about 40% of users worldwide reach Google over IPv6, with wide variation by country and network. The protocol is not backward-compatible, so networks must run both IPv4 and IPv6 (dual-stack) or use translation mechanisms like NAT64.

For most users, the switch to IPv6 is invisible. Your device may already have an IPv6 address without you noticing. The main benefit is that it removes the scarcity problem entirely, allowing every device to have a unique public address.

Frequently Asked Questions

Will I lose internet access when IPv4 runs out?

No. ISPs use NAT to share addresses, and most services work fine over private IPv4. You may notice issues with online gaming, peer-to-peer, or hosting a server, but basic browsing and streaming are unaffected.

Why don’t they just make more IPv4 addresses?

Because IPv4 uses 32-bit addresses, the format itself limits the total number. You cannot add more bits without changing the protocol, which is exactly what IPv6 does. Extending IPv4 would break compatibility with all existing hardware and software.

Is my IP address the same as my neighbor’s?

Possibly. If your ISP uses CGNAT, many customers share the same public IPv4 address. Your internal (private) IP is unique on your local network, but the public-facing address may be shared.

Can I buy an IPv4 address?

Yes, but only through brokers or transfer markets, and you typically need to justify the need to your Regional Internet Registry. Prices vary widely and are not officially regulated.

What is the difference between IPv4 and IPv6?

IPv4 uses 32-bit addresses (like 192.168.1.1) and IPv6 uses 128-bit addresses (like 2001:db8::1). IPv6 is newer, has vastly more addresses, and includes features like autoconfiguration, but it is not directly compatible with IPv4.

When will IPv4 completely run out?

There is no single date. The free pools at RIRs have been depleted at different times, but some addresses remain in the hands of organizations and on secondary markets. It will take years, possibly decades, for the last IPv4 address to be used, if ever.

Related

• How to Clear Samsung Mailbox Email, Voicemail & Storage
• Blox Fruits Codes for Devil Fruits?
• Blue Light Glasses Sleep: Do They Really Work?

in t | Total IPv4 addresses | - | 4294967296 | 0 | 4294967296
in u | Addresses in use (est.) | - | 3700000000 | 0 | 4294967296
out left | Addresses remaining | - | t - u | 0
out pct | Percentage used | % | (u / t) * 100 | 2